Thermoelectric Effects
•Three separate theories behind the operation of thermoelectric cooling first appeared in the 1800s.

•Seebeck effect: Alessandro Volta and Thomas Johann Seebeck (1821) found that holding the junctions of two dissimilar conductors at different temperatures creates an electromotive force or voltage. This is the basis for thermocouples.

•Peltier effect: Jean-Charles Peltier discovered (1834) a heating/cooling effect when passing electric current through the junction of two conductors.

•Thomson effect: William Thomson (Lord Kelvin) showed (1851) that over a temperature gradient, a single conductor with current flowing in it has reversible heating and cooling.